US2074980A - Air compressor - Google Patents

Description

March 23, 1937 N. A. CHRISTENSEN AIR COMPRESSOR m M m w N mm E R V /vm s 5. a my A m E S V T 5 U 0% C 4 Filed Oct. 17, 1932 MEL BY March 23, 1937. N. A. CHRlSTENSEN AIR COMPRESVSOR 3 Sheets-Sheet 3 Filed Oct. 17, 1932 IN VENTOR MEL: 4 6;/'/.57'MEA/ BY ATTORNEY Patented Mar. 23, 1937 3 Claims.

This invention relates generally to air compressors and an important object of the invention is to provide means for preventing the throwing of lubricant from the crankshaft into the cylinder,

Another important object of the invention is to provide inexpensive valve construction for compressors, which, under ordinary conditions have tendencies to set up a singing reed action,

but with the construction and arrangement herein provided, these valves are fioatingly retained in position to counteract any tendencies for the valves to set up humming or whirring sounds.

A further object of the invention is to reduce machining of the cylinder head to a minimum by provision of a simple and durable valve seat member.

Another object of the invention is to provide an improved form of spring for the governor control which will not be as subject to fatigue and crystallization as the more usual form of compression coiled springs employed for this purpose and will be considerably cheaper.

Other objects and advantages of the invention will become apparent during the course of the following description.

In the accompanying drawings forming a part of the description and wherein like numerals are employed to designate like parts throughout the 30 several views,

Fig. 1 is a side elevation of an air compressor with governor control,

Fig. 2 is a longitudinal vertical section of the same,

Fig. 3 is a top plan of the compressor with the head of the cylinder and governor control removed,

Fig. 4 is an enlarged perspective view of half of the improved type of baille,

Fig, 5 is an enlarged side elevation of a portion of the trigger mechanism of the governor illustrating the new type of spring release for the inlet valve,

Fig. 6 is a bottom plan of the cylinder head with 45 a dotted circular line indicating the relative operative position of the cylinder walls overlapping the ends of the valve guard for preventing accidental displacement thereof,

Fig, 6a is a fragmentary section through the 50 discharge valve of the above form of cylinder head,

Fig. '7 is a fragmentary'vertical section through a portion of the cylinder head showing the inlet 55 valve in operative position,

Fig. 8 is an enlarged perspective View of the improved valve and guard therefor,

Fig. 9 is a bottom plan of a modified form of cylinder head and valve plate assembly,

Fig. 10 is a longitudinal section of the same on line l0|0 of Fig. 9 and Fig. 11 is a transverse section of the same on line H-|l of Fig. 9,

Referring now more specifically to the drawings for further details, the numerallfl designates the crankcase portion of an air compressor having openings in opposite ends for the attachment of bearings l I, having suitable bushings for mounting a compressor crankshaft l2. This crankshaft may be connected directly or geared in any suitable manner to a crankshaft of a prime mover, not illustrated, as this connection is well understood from the prior art and my several prior patents. The bottom of this crankcase casting is closed and sealed by a removable plate I3 giving access to the enclosed parts. One side of the casting is provided with a filler l4 having an overflow to the engine crankcase as shown in Fig. 1 and the same side is equipped with an integral lateral enlargement l5 which is hollow and communicates with the interior of the crankcase at its lower end and at its upper end has threaded therein a breather tube It.

The top of this crankcase is of course open for the projection of connecting rods I l which are bored out and connected at their lower ends by bearings l8 to the crank portions of the shaft I2. This crankshaft has a longitudinally extending lubricant passage which communicates with the hollow connecting rods whereby lubricant may be forced to the upper ends thereof to lubricate the wrist pins l9 journaled in pistons 20.

The present improvements have been illustrated in conjunction with a twin compressor but of course may be employed in the manner hereinafter specified in a single cylinder compressor as will be obvious as the description proceeds.

The top of the crank case for a twin compressor is rovided with a pair of circular communicating openings defining generally the shape of the numeral 8 so that the bores of a twin cylinder 2! may register therewith as illustrated. Seats 22 are provided continuously around the edges of these openings and downwardly inclined shoulders 23, at opposite ends of the openings are provided to deflect any lubricant running down the same on to the crankshaft bearings. In order to prevent lubricant from being thrown up intothe cylinders 2|, by the crankshaft during its rotation, baflie means are clamped upon the seat 22 by bolting the cylinder portion upon the crankcase. The baflle means in the present illustration are composed of a pair of plates or stampings 24, best seen in Figs. 3 and 4, possess- 5 ing a shape generally similar to the numeral 3 in the case of a twin compressor; while in the case of a single cylinder compressor, the baffle means would be constituted by a pair of semicircular plates, or one-half of the baflles for the twin compressor. Each of the baflie plates has an outline corresponding to one-half of the seat 22 of the crankcase portion and its margin 251s fiat to snugly fit the seat 22 with the exception of portions spaced equi-distant from its straight inner edge 26 where the margin is provided with upwardly deflected and curved lips 21. The body portion of each end of each baiile plate is provided with a semi-spherical bulged orembossed portion 28 which is concentric with the adjoining 2O marginal portion of the bafi'le plate. A series of apertures 29 are provided -in the-fiat marginal portion of the bafiie plate at the-base of the bulged portion in circumferential relationship to be concentric with the semi-circular end por- 25 tions of. the bafile. In somecases, these apertures may extend into. the bulged portions :to facilitate the passage of any liquid lubricant from the cylinders back into the-crankcase. As

appreciated from Fig. 2, the openings atthe 3 ends of the bafile plates are disposed-abovethe inclined ledges or. shoulders 23 so that the latter will guide any returning lubricant and spill the same upon the crankshaft bearings.

The central portion of each bulge 28 is removed to provide each section of the bafile with an opening 30, extending from the inner straight edge-26 of the baffie plate throughout thebulged portion to touchthe flat marginal portion 25 and thereby provide, with. its complementary baiile 40 section, an elongated slot 3|, having its longest dimension diametrically of the cylinderto accommodate the projection of the connecting rod I! into the cylinders 2|. notch or opening 30 adjacent the straight edge 45 26 and the crest of the humps are flattened as indicated at 32 to be disposed substantially-in a plane parallel to the plane of the fiat margins 25. Obviously the raised portions 28 :prevent.

lubricant overflowing into openings 30 and being- 50 carried upwards by the connecting rods.

these. complementary bafileplates asshown in Fig. 4 are placed together with their straight edges 26 abutting and their fiat margins resting.

in the seat 22 of the crankcase as shown. inFig.

55 3, and with their bulged portions 28 extending upwardly and slightly into the lower ends of the. bores of the cylinder 2|. When the cylinder is bolted on to the crankcase by the bolts 33, with a gasket disposed between the bottom of the cylin- 0 der and the fiat marginal portions 25 of the bafiies, the lips 21 will be depressed into the gasket to increase the frictional lock between the parts .and to prevent accidental rattling or rotation of .the baflle plates, when used in asingle 5 cylinder compressor where the two complementary bailles form a circular bailie plate and may have a tendencyto rotate if not precluded bysuch or equivalentmeans. The slots or open.- .ings..301inthe baflles areof such dimensions to 7o afiord proper clearance for the connecting rods andyet are of a size-to preclude lubricant being. thrown up into the cylinder by rotation of the crankshaft. The openings 29 also permit the passageof. lubricant vaporup into the cylinder 75 2| .and still provide ample drainage ;of any oil- Opposite edges of each.

Two of dropping from the wrist ins, cylinders or pistons back into the crankcase.

A head 34 is suitably bolted on the cylinders 2| and incorporates therein inlet and outlet valves, the former being fed atmospheric air 5 through the passageway 35 drawn in through an air cleaner 36. An automatically acting governor mechanism is indicated in general by the numeral 31 and includes a pressure sylphon housed in chamber 38 and actuated by reservoir pressure 10 to automatically open the inlet valve. 39 when reservoir pressure reaches a predetermined amount. This type of inlet valve constructed from thin sheet spring steel is generally shown in: my prior Patent No. 1,796,040 granted March 15 17, 1931 and it is one of the objects of this invention to improve the construction of the inlet valve and guard member and obviate any hum of the valve due to air currents passing the same setting up a reed action. The construction of 20 thecylinder head'in Figs. 6 and'l and theformation of the-valve and guard seats is generally the same as in my previous patent, it being noted: that the valve seats and parts have-their center' line located in a chordal line relative tothe bore 25. of the cylinderas-indicated in-dotted lines in Fig.6.

The inlet ports 39 from passage 35 extend into the bottom of a valve seating. recess, against which a floating-valve 4| of. thin sheet spring steel normally seats under its inherent-spring action and close confinement. A valve guard 42 n of less width than therecess 4ll=is provided for retaining the valve in operative position and alsohas the functionof preventing brokenvalves 3 from. falling into the cylinder. One end .43-.of the guard member is provided with a pin 44 having a fairly loosefit inv a cavity 45 provided in the bottom of the recess 40, the pin passing throughan aperture .,46.in one end of the leaf 40 spring valve with sufficient clearance to.prevent the spring valve 44 being held toorigidly at one end. This end of the ,valve guard is provided. adjacent the pin-44with a transverse shoulder 41 having a height slightly greater than the thick-' ness of the leaf spring valve 4|.- The surface 43 of the guard member next.to the leaf spring valve is tapered from artransverseshoulder 42' adjacent the pin 44 "to a point adjacenttheother end of the guard where the surface then is angularly disposed ina plane parallel to-its outer surface. The end of the guardisseated-in arecess 49 in the bottom-of the cylinder-headso that the entire outer surface of the valve guard member is flush with the under surface of the cylinder head whereby opposite ends of the guard member will fit flush on the upper surface of the. cylinder wall. Thechordalarrangement of theguard member across the bore-ob the cylinder with its ends resting ,upon thecylinder walls prevents the. guard andvalve fromfallingrinto. the bore. It will also be obvious that thevalve 4| in opening and closing, flexes on the shoulder. 42" rather than at the pin 44.

As explained in the aforesaid patent, the govt5 ernor control includes a push pin'fl5fl slidably mounted'in the'cylinder head for engagement with the'free end of the valve 4| to hold thesame in open position when reservoir pressure has reached a predetermined-quantity.- As bettershown in Figs.- 2 and 5, the upper ends of -the push pins are provided with heads 5| normally retained in engagement withthe undersidepfa trip pin 52 carried .by a-trigger member-530i the governor control.

As shown in-Fig.; 2, light compression springs 54 have been employed, heretofore, for retaining the push pins 5% in elevated position whereby the inlet valves may close upon their seats. This compression spring should be of strength sufficient to overcome the weight of pin 50, but due to slight vibrations at high motor speeds and due to production differences in workmanship and material from which these springs are made, it has been found necessary to materially increase the strength Olf these springs beyond the mere weight of the pin 50 to such an extent as to set up a factor which may materially affect the normal operation of the governor. For these reasons a different type of spring has been provided as illustrated in Fig. 5.

As will be readily seen, this new type of spring shown in Fig. 5 imposes no functions interfering with the normal governor operation. and its strength can vary within large ranges. This modified spring comprises an intermediate coil portion 5 1' with one end extended horizontally and looped about push pin 59 under the head 5!. The other end 55 of the spring is directed vertically and then horizontally to be disposed in an annular groove in one end of the pin 52 and partially coiled thereabout to prevent accidental displacement. Such a spring yieldingly retains the head of the push pin 50 against the under side of the pin 52 so that it is elevated with pin 52 and the inlet valve functions when reservoir pressure has not reached the maximum degree. It is of course understood that the finger 53 is depressed by a spring pressed plunger 56 sliding over the tapered nose of the trigger whenever reservoir pressure swings the spring pressed plunger 58 vertically and exerts pressure on the trigger 53 to move the pin 50 downwardly and thereby unseat the inlet valve so that on the compression stroke of the pistons, the air drawn in will be idly forced out to the atmosphere. However, with the push pins 5% in the position shown in Fig. 2, the inlet valves are free to seat and do so after their opening movement is compelled by the downstroke of the pistons and the compressed air is then forced out through suitable ports and outlet valves 51 to the reservoir.

As illustrated in Figs. 6 and 6a, the outlet valves comprise small triangular plates 58 adapted to be forced to their separable seats 58 concentric with outlet ports 59 by means of small coil springs 60 carried in axial cavities of cap screws 6! threaded into openings concentric with the ports 59. As will be noted in Fig. 6, the valve plates 58 are substantially triangular shaped with their apices removed and are of such dimensions as to have free movement perpendicularly of their seats but not laterally thereof. Air pressure within the cylinder obviously unseats the valves, and permits escape of air through suitable discharge passages; the springs Gil serving to return the triangular valve plates to their seats upon the suction stroke of the piston. The lift of the outlet valves of Fig. 6a is governed by the distance between their seats 58' and the inner ends of the cap screws 6|, necessitating accurate disposition of the valve seat carrying shoulder and adjustments of the cap screws.

In Figs. 9 to 11 inclusive, a modified form of cylinder head and valve carrying member is illustrated. In this form of device no valve seat surfaces are provided in the cylinder head and thereforea minimum of machining thereof is necessary due to the provision of a novel valve carrying member or plate indicated in its entirety by the numeral iii. Moreover, this new association'of parts obviates the necessity of separate guard members for the valves and makes its possible to locate the inlet valves centrally of the cylinder bore if desired and dispenses with the chordal arrangement of guard plates shown in Fig. 6.

The cylinder head 3 is cast with an inlet' passage 62 communicating with the lateral inlet port 63 and an exhaust passage 64 communicating with a lateral exhaust port 85. The exhaust passage 64 is provided with an outlet port for each cylinder as best seen in Fig. 11, while the cored out inlet passage 52 is provided with an inlet port 61 for each cylinder.

A. valve seat carrying member or plate 10 is clamped between the cylinder head 34 and the cylinder 2! with suitable gaskets interposed to seal the joints. The surface of the member 10 adjacent the cylinder head is provided with an elongated substantially oval cavity 'H above each cylinder bore in communication with an inlet port 6? for the reception of a correspondingly shaped steel valve seat element 12, the upper surface of which is flush with the upper surface of the element of the member '19. This valve seat element 732 is provided with a plurality of apertures '13 in registration with the inlet port 6'! and adjacent one end is provided with a perforation M, for the reception of a pin "l5 fixed in plate 16 and adapted for floatingly mounting a valve plate 76 constructed of thin resilient sheet steel. The valve seat or plate 72 is reversible to present either top or bottom surface as a valve seat as shown in Fig. 10, and has its opposite ends beveled off in the same direction to provide a lip at one end under which a suitable tool can be inserted for lifting the seat out of plate 19. Either the arcuate ends of the cavity 'i' i or the ends of the seat 72 can be cut off with a straight edge to provide a space between the plate and its cavity to facilitate entry of the tool to lift the seat. Of course, the upper gasket effectively prevents leakage between the members 10 and 72. A valve cavity or recess I7 is located beneath the recess H and being shorter in length, provides the recess ll with shoulders at opposite ends to seat the plate 12. The bottom wall of the cavity H at one end is just a few thousandths of an inch deeper than the leaf spring is thick and is substantially parallel to the upper surface of the member 70 to loosely receive one end of the spring valve 16. This end of the valve has an aperture to loosely admit the pin 15. The bottom of this end of cavity 11 adjacent the pin 75 gradually deepens toward the end of the cavity opposite the pin 15 thereby providing the bottom wall with a transverse shoulder 18 upon which the spring valve flexes when moved to an open position upon the downstroke of the piston. The intermediate portion of the cavity "H is enlarged laterally to communicate at opposite sides with a pair of elongated parallel inlet ports 19 extending all the way through the inner surface of the member 70. In order to automatically unload the compressor when predetermined pressure in the reservoir is established, a governor mechanism 3! may be provided as in the preceding application with the push pins 50 depending through one of the inlet openings 13 of the valve seat element to flex the valve 56 to an open position; such flexing of the valve occurring in proximity to the shoulder 18 when maximum suction is created by the downstroke of the piston.

The valve carrying member H! above each cylinder bore is also provided with an exhaust port SUI-which-extends all the way through the member 10' to communicate with. the exhaust passage 66.

This exhaust port 80 intermediateits ends is reduced in diameter to provide a valve seat portion or annular shoulder '81 for the reception of a. triangular shaped free floating valve 82 normally held upon'its seat by a coil spring 83 fitting within a cavity 84 of the cylinder head. These exhaust valve plates have a free riding fit within the enlarged portion of the exhaust ports above the seats and are automatically lifted therefrom upon the upstroke of the piston to admit the discharge of compressed air into the passage 64. The cavity 84 extends through a boss 84' extending into the passage 66 directly above the port 80. This boss serves as a stop to limit the lift of valve 82 and consequently the lift is determined by the depth of the enlarged portion of port 80 and the thickness of the gasket, thereby eliminating several fussy dimensions necessary when the construction of Fig. 6a is employed.

From the foregoing description, it will be seen that all of the fine machining of valve seats and valve attaching means is performed upon the separate valve carrying member 10 rather than upon the cylinder head and that as a consequence of this construction, no separate guards for the inlet valve are required as in the modification shown in Figs. 6 to 8 inclusive. However, as in the preceding modification, the inlet valves are floatingly retained in operative positions and in such manner as to preclude the setting up of any humming action of the valves when in operation.

Furthermore, by reason of the independence of the valve carrying member from the cylinder head, the passages in the latter can be readily cleaned of carbon or other foreign matter as well as the valve seats which can be easily taken out of the member '16 and cleaned or polished without disturbing .or removing plate 10 from the cylinder.

It will of course be understood that these improvements are applicable to a single cylinder compressor as well as .toiprime movers and other types ofipumps. It is also to be understood that various changes in thesize, shape and arrangement of parts may be resortedto without departing frorn thespirit. of the invention or the scope of'the appendedclaims.

I claim:

1. In acompressor, the combination of a crankcase portion,. a cylinder portion having a bore, said crank case portion; having a recess surrounding the same, a piston operable in said bore and having aconnecting rod extending into the crankcase portion,.and an'oil baffle havig a substantially' flat margin seated in said recess and provided with a. deflected lip adapted to be sprung and clamped in the recess between.;the cylinder and the crankcase portions.

2; Ina compressor, the combination of a crank case having an openingbordered by a recess, a cylinder having a bore in substantial alignment with saidopening'a piston'operable in said bore and having-a connectingsrod extending into the crankcase, an oil baiile having, a substantially flat marginiseated in said recess',=and a gasket between the crankcase and cylinder and overlying the flat marginof the baffle.

3. In 2 a compressor, the combination of a crankcase portion having an opening,'a cylinder portion havinga bore registering with said opening, saidcrankcaseportion and cylinder having complementary seating surfaces, the seating surface of the crankcase portionrbeing overhung by a corresponding portion 'of the cylinder and beingprovided: with a baiile recess bordering the- NIELS :ANTON' CHRISTENSEN.-

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